U.S. Pat. Nos. 4,079,341; 4,149,127; 4,187,476; 4,307,352; 4,331,940; 4,333,062; 4,357,582; 4,435,688; and 4,445,097 disclose oscillators stabilized by single dielectric resonators.
Stiglitz, M. R., "Frequency Tuning of Rutile Resonators", Proceedings of the IEEE, March 1966, pp. 413-414, shows, in a waveguide environment, the effect on tuning range when one disk of a double dielectric resonator is made thicker than the other disk.
Karp, A. et al., "Circuit Properties of Microwave Dielectric Resonators", IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-16, No. 10, October 1968, pp. 818-828, discusses tuning of multiple dielectric resonators.
Gerdine, M. A., "A Frequency-Stabilized Microwave Band-Rejection Filter Using High Dielectric Constant Resonators", IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-17, No. 7, July 1969, pp. 354-359, discusses temperature compensation of multiple dielectric resonators.
U.S. Pat. No. 3,475,642 discloses the use of several dielectric resonators as a slow wave structure.
Fiedziuszko, S. et al., "Double Dielectric Resonator", IEEE Transactions on Microwave Theory and Techniques, September 1971, pp. 779-781, calculates and measures the resonant frequency of double dielectric resonators from their physical dimensions and dielectric constants.
Maj, S. et al., "A Composite, Multilayered Cylindrical Dielectric Resonator", 1984 IEEE MTT-S Digest, pp. 190-192, analyzes multiple dielectric resonators.